Check valves for fluid administration systems are well known, particularly in the medical field where it is desirable to have a valve which quickly returns to the closed position when flow is reversed in an intravenous system or the like. Conventional backflow check valves are normally closed devices that open only when subjected to an increase in flow pressure. When the pressure is reduced, the valve quickly returns to the closed position. Typical valves are disclosed in U.S. Pat. Nos. 4,246,932, 4,286,628, 4,310,017, 4,369,812 and 4,422,407.
U.S. Pat. No. 4,535,820 also describes a one-way flow valve. This assembly can be used in a system for injecting fluid into a container such as an intravenous fluid bag. The '820 patent teaches a normally closed valve which permits only one-way flow into a container. One cannot remove or withdraw fluid from a container with this device.
U.S. Pat. No. 4,683,916 describes a two-way, normally closed reflux valve which permits both injection and aspiration of fluid into and out of containers. When used with a needleless system, the blunt syringe engages a valve plunger which moves the valve disc and holds it away from the valve seat, permitting flow in both directions depending on the action of the syringe. When the syringe is disconnected, the disc-positioning force is removed and the disc returns to its normally closed position against the valve seat.
In a hospital type environment, medications and/or pharmaceutical solutions are typically stored in large containers at pre-selected concentrations. These containers are frequently located in common areas which are accessible to a large number of health care providers. When administering patient care, individual workers frequently withdraw fluid from these containers to administer or formulate medications and other therapeutic solutions.
Known two-way valves can be used with a piercing device or spike to withdraw fluid from receptacles containing pharmaceutical solutions. But, there are hazards associated with these two-way systems during end-use application. For example, known designs allow medical technicians to withdraw a volume of solution from a container, administer it to a patient and return the unused portion to its original container, possibly causing the introduction of contaminants and infectants. Unused fluid from a syringe which is reintroduced to its container may also alter and/or dilute the original fluid concentration. These disfavored practices are prevented with the valve of the present invention.
Another problem with two way valves is that the contents of a syringe can be accidentally introduced to a container having a different solution, i.e., not the container from which the fluid was originally withdrawn. Under these circumstances, the result could be a harmful, toxic or even fatal mixture of medications or fluids.
To avoid these pitfalls, there is a need in the art for a one-way aspiration valve which allows for withdrawal of fluid from a container, but which does not allow an injection back into the same or different container. The present invention overcomes the problems associated with conventional devices by permitting aspiration only with no possibility of reverse flow in the opposite direction.